Anatomy - Week 7/8 PP Flashcards
Types of Tooth Tissues
Enamel
Dentin
Pulp
Cementum
Enamel
hardest structure in our bodies - harder than bone
-originates from the ectoderm
-formed by ameloblasts
-not a living tissue (mature enamel does not contain cells that are capable of repair and regeneration, no blood supply or nerves)
-It is permeable - allows for the exchange of ions, allows for demineralization & remineralization
-composed of inorganic (mineral) and organic substances
Preservation of Enamel
- Preservation is the goal of dental health professionals
-Consider properties & histology
*determining caries risk
*counselling patients/communities on fluoride use
*Application of sealants and restorations
*use of the correct polishing and toothpaste agents
Mature enamel composition
Approximately 96% inorganic materials and 1% organic
materials (1%) and water (3%)
Main mineral component
Calcium hydroxyapatite
§ Found in lesser extents in dentin, cementum and bone
§ Appears more radiopaque on a radiograph
◦ Other minerals also present in smaller amounts
* Carbonate, magnesium, potassium, sodium and fluoride
Thickness of Enamel
A thick as 2.6mm at cusps of molar teeth
-thinner at incisal edgers
Color of enamel
-Translucent
* Colour varies
* yellowish to grayish/bluish white
* Varies with age
* Primary teeth
* Whiter
* More opaque crystalline form
* Permanent teeth
* Yellowish-white to gray
* Reflects underlying dentin
Macroscopic Structure
Appears Hard, shiny & Translucent
Histology of Enamel
Lines of Retzius - Incremental lines - represent the deposition of enamel during the formation of a tooth
Hunter-Schreger bands - alternating light and dark bands - caused by enamel prisms changing direction
Enamel is composed of…
Enamel Rods also known as enamel prisms
* Crystalline structural unit of enamel
* Extend from the surface of the tooth to the DEJ
* Grouped in rows and organized around the
circumference of the long axis of the tooth
* Rows are generally perpendicular to the surface of the tooth
Enamel Rod Structure
-Rod Sheath
*covering of the enamel rod
*acid resistant (hardest enamel structure)
-Inter-rod substance (interprismatic substance)
*the material between the keyhole shaped enamel rods
*like a cement or glue
How do you think the arrangement of the enamel rods influences the penetration of decay? Do you think the rate of decay slows or increases once it reaches the dentin?
Penetration of decay follows the pattern of the rods
Decay will increase once it reaches the dentin as it is less mineralized
What are Enamel Lamellae?
Enamel lamellae are partially mineralized vertical sheets of
enamel matrix that extend from the DEJ near the tooth’s cervix to the outer occlusal surface
What are Enamel Tufts?
Enamel Tufts are noted as small, dark brushes with their bases near the DEJ
Enamel Spindles
They represent short dentinal
tubules near the DEJ junction.
* odontoblasts that crossed the basement membrane before it
mineralized into the DEJ.
* dentinal tubules become trapped
during the appositional growth of
enamel matrix, which becomes
mineralized around them.
* Clinical implications of enamel
spindles are unknown at this
time (
Abfraction
Enamel can also be lost as a result of abfraction. Abfraction is thought to be caused by tensile and compressive forces during tooth flexure, which possibly occurs during parafunctional habits with their occlusal loading
Clenching & grinding
happens only on cervical 1/3 of tooth
Parafunctional habit ^
Attrition is..
the wearing away of hard tissue as a result of tooth-to-tooth contact.
Abrasion is..
is the wearing away of tooth surface caused by friction or a mechanical process. Abrasion happens when teeth are brushed too vigorously in sweeping horizontal strokes. The use of a hard toothbrush can also cause the problem.
Erosion is..
This can happen with bulimia and gastric reflux as well as overusing acidic drinks (even in baby bottles) or foods
*meth mouth is a type
Lemon water is another cause
Dentin is..
- makes up bulk of tooth
-not clinically visible
*usually covered by enamel or cementum (exceptions - attrition or abrasion of enamel or cementum)
Dentin Origin
Dental papilla > mesenchyme cells
Dentin - living tissue?
Odontoblasts (dentin producing cells) are present throughout life of a tooth to continuously produce dentin
Dentin Calcification
Softer than enamel (less calcified)
◦ More flexible than enamel
§ Less mineralized - more radiolucent on a radiograph
Dentin Composition
Inorganic Substance (hydroxyapatite crystals) - 70 %
Organic substance (proteins) - 20%
Water - 10%
Dentin appearance
Resemblance to Bone
◦ Harder than bone and cementum
§ Resembles bone in physical and chemical properties
Colour of Dentin
Yellow
§ Clinical color of a tooth – can be seen through translucency of enamel
Dentinal tubule
Long tube running from DEJ/DCJ to pulp
* Least mineralized
* Contains odontoblastic process Provides nutrients to dentin
* May play a role in pain sensation of a tooth
* Arrangement
* Apex and cusp areas: straight and perpendicular to DEJ/DCJ
* Sides of tooth and top ½ of root: S-shaped
Dentinal fluid
The extravascular fluid which appears on the surface of freshly cut dentin
* Composed of mainly cytoplasm from odontoblastic process
Dentin - Odontoblast process
long cellular extension of the cell inside the
dentinal tubule
* still attached to the cell body of the odontoblast in the pulp
Types of Dentin
Peritubular dentin - walls of the dentinal tubules
Intertubular dentin - between the tubules, bulk of the dentin
Types of Dentin by Time of Formation
Primary dentin - dentin formed before eruption, forms the bulk of the tooth, generally deposited evenly, with regular pattern of tubules
Secondary Dentin - formed after eruption due to normal occlusal forces, purpose is to protect pulp, formation - regular with mild deviation from original pathway
Tertiary (Reparative) dentin: formed in response to trauma, purpose is to protect pulp, formation is irregular
Development of Dentin
Odontoblasts are the dentin producing cells
-lays predentin
-as it moves, it leaves part of its cell
*causes cell wall to stretch/lengthen
-Odontoblast cells remains in pulp
-Only odontoblastic process is mineralized tissue (tube)
Dentinal Hypersensitivity
different than sensitivity associated with decay (more dull and chronic)
The discomfort that is triggered is the short, sharp pain of dentinal hypersensitivity. The pain from other
tooth-related problems, such as caries or pulpal or gingival infection, is usually dull and chronic
Treatment of Dentinal Hypersensitivy
Dentinal hypersensitivity can be treated somewhat successfully with solutions applied either by
professionals or within dentifrices. These desensitizing agents either temporarily block the exposed open
ends of the dentinal tubules. However, in severe cases, restorations sometimes are the only way to reduce hypersensitivity of the exposed dentinal surface
If the outer layers of enamel are lost with aging, such as with attrition. How is a clinician able to differentiate between enamel and dentin?
The newly exposed dentin on the crown is various shades of yellow-white and appears rougher in surface texture than enamel.
Do you think attrition in dentin would occur at the
same rate, faster or slower than that of enamel?
Attrition in dentin can occur at a more rapid rate when it is exposed because its lower mineralized content
How can root dentin become exposed? What surgical procedure may be performed to correct this
dentin root exposure?
Root dentin can be exposed when the thin layer of cementum is lost as a result of gingival recession, with
its lower margin of the free gingival crest
A gingival graft is a generic name for any of a number of surgical periodontal procedures whose combined aim is to cover an area of exposed tooth root surface with grafted oral tissue
Pulp - location?
Location
* Occupies pulp chamber in crown
* Occupies root canals in roots
* Enclosed by dentin
Development of Pulp
Comes from dental papilla
§ It is the only non-mineralized tissue of a tooth and consists of
blood vessels, lymph tissue and nerves.
Cells of Pulp
Fibroblast cells
◦ Predominant cell type in pulp
◦ Mesenchymal cells which become fibroblasts
◦ Are responsible for the formation of intercellular substance in the pulp
Is pulp mineralized or non-mineralized?
ONLY NON MINERALIZED TISSUE OF THE TOOTH
Odontoblasts in Pulp
Odontoblasts
* Only the cell body is in the pulp
* Odontoblastic process is in dentin
* Originated from mesenchyme
* Produces dentin
* Dentin pulpal wall changes position over time
* Formation of secondary/reparative dentin and narrowing of the pulp
Histocyte cells - in pulp
Histocyte cells
Start as undifferentiated mesenchymal cells
* Localized around capillaries
* Part of pulp’s defense mechanism – respond
to injury
Lymphocytes in Cells
Localized around capillaries
§ Specialized WBC
§ Defense mechanism
o T-cells - defense
o B-cells –antibodies
Intercellular Substance of Pulp
Korff’s Fibers
§ In intercellular substance
§ Fibrous substance - appears as coiled rope
§ Mostly functional role: forms dentin matrix
Other components of Pulp - Blood vessels and Lymphatic vessels
- Supply oxygen and nutrients and take away CO2 waste
- Plentiful in young pulp
- Superior and inferior alveolar artery enter via apical foramen
Other components of Pulp - Nerves
2nd division of Trigeminal nerve – sensation maxilla
* 3rd division of Trigeminal nerve – sensation mandible
Denticles (pulp stones)
Mineralized bodies of irregular rounded shape
◦ Location:
§ Free in soft tissue of pulp
§ Attached to dentin surrounded by secondary dentin
◦ Various Shapes
§ Size increases with age
◦ Dental concerns
§ Problems with endo treatment
◦ Never a source of infection
*mineralized tissues right in center of pulp
Pulp components - diffuse mineralizations
Known as false pulp stones
§ Diffuse calcifications
§ Small thin scatterings of calcified material
§ Found in older teeth or those with root canals
§ Usually of no clinical significance
3 Pulp Zones
- Odontoblastic Zone
- Cell Free Zone
- Cell Rich Zone
Pulp Zone #1 - Odontoblastic Zone
Cell bodies of odontoblasts that line outer pulpal wall
§ First line of defense
* Forms dentin – primary and secondary
Pulp Zone #2 - Cell Free Zone
§ Fewer cells than odontoblastic layer but not 100% cell free
§ Buffer area
§ Movement area for other zones especially when secondary/reparative
dentin is forming
Pulp Zone #3 - Cell Rich Zone
Reservoir of undifferentiated cells
§ New odontoblasts, defense cells
◦ Extensive vascular system
◦ WBC for defense
Functions of the Pulp
- Formative – in development of tissues § Odontoblasts for forming dentin
- Korff’s fibers – fibrils in dentin – forming ground
substance/matrix for dentin - Sensory function
- Nerve fibers in pulp – sensation of pain
- Nerves capable of pain only when stimulated
- Sensation of pressure from nerves connected to the pulp from
the PDL – nerves outside of tooth - Nutritive function
- Nutrients delivered from bloodstream
- Supplies itself and odontoblast with nutrients - Defense Function
- Inflammatory reaction – if pulpal damage or irritants to the pulp
- Production of sclerotic dentin –calcium salts
- Production of reparative dentin – odontoblasts - Vitality
- Keeps the tooth alive
- Keeps tooth enamel from becoming excessively brittle
* Endodontic tooth – non vital – perfectly fine but can become brittle
over time
What are pulp stones & should we be worried?
- These are calcified masses (true); in other cases, they are amorphous in structure (false).
- They are quite common and may fill most of the pulp chamber. They are detected as radiopaque
masses in radiographs and are only a problem during endodontic therapy
Dental hypersensitivity
can be treated successfully in some cases with solutions applied either by professionals or within over-the-counter products available to patients
These desensitizing agents, many of which are also used for caries control, remineralize the tooth (fluoride and casein phosphopeptide-amorphous calcium phosphate [CPP-ACP]), temporarily block the exposed open ends of the dentinal tubules (similar to the process of tooth staining) or interfere with the nerve transmission to stop it completely such as with local anesthesia of the pulp. However, restorations sometimes are the only permanent method to reduce hypersensitivity of the exposed dentinal surface in severe cases. Methods that will fully seal the exposed dentinal tubules and thus prevent any dentinal hypersensitivity are being studied
Pulp
Endodontics (ex. specialists of the pulp)
When the pulp is injured by cavity preparation through mechanical or chemical injury and even by extensive caries or by traumatic injury, it may undergo inflammation or pulpitis
This inflammation of pulpitis initially remains localized within the confines of the dentin . This pressure from this confined pulpitis can result in extreme pain as the inflammatory edema presses on the afferent nerves contained in the pulp - this is an emergency!!!
- Pulpitis can later cause a pulpal infection in the form of the periapical abscess or cyst in the surrounding periodontium, spreading by way of the apical foramen – will have to be “popped” like a pimple, patient will be on antibiotics
- If the pulp dies from the infection, it must be surgically removed
The gingival description - the colour
Signs of health - pale pink, darker in people with darker complexions due to melanin pigmentation
Changes in disease - in chronic inflammation: dark red, bluish red, magenta, or deep blue
- in acute inflammation: bright red
Gingival Description - Size
Signs of health -free gingiva: flat, not enlarged, fits snugly around the tooth.
Changes in Disease - free gingiva and papillae: -may be localized or limited to specific areas or generalized throughout the gingiva, the col deepens as the papillae increases in size
Enlargement from Drug Therapy: certain drugs used for specific therapy cause gingival enlargement as a side effect such as phenytoin, cyclosporine, and nifedipine
Gingival Description - Shape
Signs of Health:
Free Gingiva: * Follows a curved line around each tooth; may be straighter along wide molar surfaces. * The margin is knife-edged or slightly rounded on facial and lingual gingiva; closely adapted to the tooth surface
Papillae: * Facial and lingual gingiva are pointed or pyramidal papillae with a col area
under the contact between adjacent teeth. * Spaced teeth (with diastemata). Interdental gingiva is flat or saddle shaped
Changes in Disease
◦ Free gingiva: rounded or rolled. ◦ Papillae: blunted, flattened, bulbous, cratered
* “McCall’s festoon”
* “Stillman’s cleft” * Floss cleft
Endodontics
- when pulp is injured by cavity preparation through mechanical or chemical injury, and even by extensive caries or traumatic injury, it may undergo imflammation or pulpitis.
- this inflammation of pulpitis initially remains localized within the confine sof the dentin. however, the pressure from this confined pulpitis can result in extreme pain as the inflammatory edema presses on the afferent nerves contained in the pulp.
- pulpitis can later cause a pulpal infection in the form of a periapical abscess or cyst in the surrounding periodontium, spreading by way of the apical foramen.
- if the pulp dies from the infection, it must be surgically removed
Clinical observations
- Accurate patient evaluation and treatment planning requires a
thorough clinical examination. This includes taking a look at the
extra-oral, intra-oral and oral mucosa structures. In Dent 237, you
will learn how to review these anatomical structures. * On the SAIT Clinical Observations form, only abnormalities are
recorded for extra and intraoral findings. If you do not observe an
abnormality when examining the extra-oral and intra-oral anatomical
structure, you will write, “no abnormality detected” (NAD) in the
space provided for each area. All gingival observations findings will
be recorded (abnormal or not).
Gingival Description - Consistency
Signs of Health
Firm when palpated with the side of a blunt instrument (probe).
-Attached gingiva is bound down firmly to the underlying bone
Changes in Disease
oSoft, spongy gingiva
* the tissue appears red, may be smooth and shiny with loss of
stippling. * tissue may be friable or thin and fragile.
oFirm, hard gingiva
* the tissue may appear pink and well stippled.
oRetraction of the margin away from the tooth
* Normally, the free gingiva fits snugly about the tooth
Documentation example
- Descriptive material to show disease symptoms
- Example:
1. Colour : normal pigmentation, generalized dark reddish colour of the free
gingival margin and interdental papillae
2. Size: generalized slight enlargement of the interdental papillae
3. Shape: localized mildly bulbous areas in the maxillary anterior
4. Consistency: generally soft and spongy, shiny surface
The Gingival Description - Surface Texture
A. Signs of Health o Free gingiva: smooth. o Attached gingiva: stippled (minutely “pebbled” or “orange peel” surface).
o Interdental gingiva: The free gingiva is smooth; the center portion of each papilla is stippled
B. Changes in Disease o Inflammatory changes: may be loss of stippling, with smooth,
shiny surface.
o Hyperkeratosis: may result in a leathery, hard, or nodular surface.
o Chronic disease: Tissue may be hard and fibrotic, with a normal pink color and normal or deep stippling
The gingival description - position
A. Signs of Health
◦ For the fully erupted tooth in an adult, the apparent position of the gingival margin is at the level of, or slightly below, the enamel contour or prominence of the cervical third of a tooth
B. Changes in Disease
◦ Gingival enlargement
◦ Gingival recession
